


And I'll Be Here Every Year, Every Christmas

by OreoAmbitions



Series: The Trebuchet Multiverse [1]
Category: Supergirl (TV 2015)
Genre: Alternate Universe, Angst and Feels, Christmas, Christmas Fluff, F/F
Language: English
Status: Completed
Published: 2019-12-19
Updated: 2020-01-04
Packaged: 2021-02-26 04:21:09
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 15,375
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21857494
Author URL: https://archiveofourown.org/users/OreoAmbitions/pseuds/OreoAmbitions
Summary: The alternate universe Supercorp Christmas AU literally no one asked for in which Cisco Ramon builds an interdimensional-trebuchet, Kara falls for Lena in far too short a time, and Lena discovers that Christmas miracles are A Thing.
Relationships: Kara Danvers/Lena Luthor
Series: The Trebuchet Multiverse [1]
Series URL: https://archiveofourown.org/series/1756471
Comments: 64
Kudos: 406





	1. Chapter 1

**Notes for the Chapter:**

> All of my time and attention has gone into Snowbird lately, chapter two of which has required extensive reviewing, so this has received virtually zero editing. It's just a little xmas fun anyway. Short sweet updates spaced a few days apart from now until New Years. Enjoy!

Lena Luthor is many things. She's the unwanted daughter of the Luthor family, the shrewd CEO of L-Corp, the cold shoulder at business parties she'd rather have missed. She's a powerful woman and a broken heart, a quick wit and a quiet humor. And once a year, for a few hundred of National City's most precious children, she's also Santa Claus.

Well, maybe she doesn't wear the suit and the beard, but she puts the hat on and she goes room to room in the cancer wing of the children's hospital. She sits on each bed, looks each child in the eye, learns each name, and finds out what each young patient would like for Christmas. Sometimes they're simple things, like a new doll, or a video game that has just come out, or a stuffed bear big enough to cuddle away all the frightening noises that fill the hospital at night. Sometimes they're impossible things. There's the little boy who wants his mother not to cry so much anymore. There's the girl who wants her sister not to be afraid of her wires and her tubes. Those are difficult conversations, and Lena finds herself casting about the room for clues to a more tangible gift. Sometimes the parents clue her in; sometimes they try to pass her money where the children can't see, anxious, apologetic, and full of sorrow. All the while, Jess follows quietly behind, jotting it all down so that Lena doesn't have to remember.

But Lena does remember. She remembers every face, and every name, and every Christmas wish - even the ones she can't breathe life into. She remembers them and she thinks of them late at night, sipping her drink on the balcony, pondering all the things she'd like to say to God should she ever get the chance. The conversation always begins with "How dare you," and only heats up from there. Lena is pretty sure she's going to hell anyway, which she assumes means she's unlikely to get any divine face time, but why waste an opportunity to be prepared?

This year the visits take place on the 21st. It's late in the season because LuthorCorp has been hard at work resolving a technical issue with a pre-holiday product launch and Lena's presence has been required everywhere from board rooms to press conferences to personal meetings with disappointed customers who need personal reassurances that all will be made well. By the time it was all sorted it wasn't really practical to play personal Santa Claus, but Lena isn't the sort of person to be dissuaded by a little impracticality. So it's done, and she's already authorized overtime for everyone who's staying in the office so close to Christmas in order to make sure the gifts are acquired and delivered on time.

The fact that Lena is now drinking alone in her living room on what is the longest and darkest night of the year, contemplating the cosmic unfairness that is cancer in children at all but especially cancer at Christmas of all fucking times, strikes her as a delicious irony. Long dark thoughts for a long dark night. How fitting.

This is what she is thinking about, her eyes on the lights twinkling in the distant hills, when she hears a soft sound move through the apartment. She dismisses it as the wind at first and then, silently wondering if she's had more to drink than she realizes, she reminds herself that wind generally speaking belongs outside of the apartment on a cold night in December when the windows are all closed. She's just resolved to rouse herself from the couch and check to be sure that she hasn't left anything ajar when someone clears their throat softly behind her.

It is a testament to her Luthor upbringing that she doesn't throw her drink in fright. She doesn't turn around either. She takes a long, deep pull of her whiskey, and then she gestures to the open bottle on the coffee table.

"Would you like a glass?" she offers.

The stranger chuckles. He moves into her line of sight then, and his fingers ghost briefly over bottle before he abandons it and slouches into the empty chair across from Lena instead. He says nothing for some time, giving her ample opportunity to consider him even as he considers her.

There are a few possibilities here. The first is that somehow this middle aged man has made it past the extensive security protecting Lena's apartment building generally and Lena's apartment specifically and has arrived here intending to do harm. In which case Lena is inebriated but not so inebriated that she isn't confident she can reach the gun secured to the bottom of the coffee table long before he is aware of its presence. The second possibility is that Lena is in fact so inebriated that she has begun to hallucinate, which given his strange attire - fur lined boots, leather pants, a long red tunic, all trimmed in an intricate pattern with which Lena is somehow vaguely familiar - is not outside the realm of the probable.

"I'm Father Christmas," he says.

Lena raises both of her eyebrows and takes another drink. If she's already hallucinating, another glass probably isn't going to make things much worse.

"Have you come to show me the ghosts of Christmas past, future, and present?"

He offers her a polite smile that says _yeah, because I've never heard that one before_. "No. I'm here to offer you a gift."

Lena nods slowly. "The real life Santa Claus comes to National City at last with a bag of Christmas miracles. Aren't there a few hundred thousand people out there more deserving?"

"No." He regards her curiously. "You don't know why I've come?"

Lena, having spent the last hour drinking and meditating on unfairness, has rather a lot to say about why he should have come, early and often, but not to the penthouse of the wealthiest person in the whole damned city. She fixes him with a dead stare.

"You are either a hallucination or a incredibly ballsy liar."

"Did you know there's only one Father Christmas in all the multiverse? An infinite number of worlds and only one of me. And I am bound by some of the same rules you are: I am bound by time, space, and the needs of the physical form. I can only be so many places at once; I can only work so many miracles."

It doesn't escape Lena's notice that 'so many places at once' doesn't necessarily mean 'one place at a time' but she doesn't press the point. There's a strange man in her living room, and she's drunk and tired and he is interrupting her annual wallowing.

"Then don't waste a miracle sitting here with me," Lena says. She nods towards the city. "There are people out there who need you. I don't. As you can see, I've done rather well for myself."

"You've done rather well for them too. Every year, every child in that hospital, and never a word in the papers. For six Christmases. Do you know what a gift that is? There is only one Father Christmas, Lena, but the Christmas Spirit lives-"

"If you say the Christmas Spirit lives in me, I will call security and have you thrown out of this building faster than you can say bah humbug."

"The Christmas Spirit lives when we breathe life into it. As you have. And so I have come to offer you a gift, to show my gratitude that you were here for these children, that you offered them your attention and your earnest affection in a time of great need. What is it you wish for?"

Lena laughs bitterly. "What do you get the girl who has everything? I inherited my brother's kingdom; all that's missing is Prince Charming. Can you offer me world peace? Can you end cancer? Can you get me an audience with the man upstairs? There are some things I've been meaning to say to him; I have a speech ready."

Father Christmas smirks. "Even I can't get an audience with the man upstairs. But I can get you your Prince Charming."

Lena closes her eyes with a long sigh. What is it they say in all the stories? Be careful what you wish for; a wish is a complicated, dangerous thing. She should hold her tongue. Holding her tongue has never been her finest talent.

"You do that," she murmurs. "You bring me my Prince Charming, and we can live happily ever after in our pretty tower while the rest of the world rots in the streets below. Is that what you want? Offer your miracles to someone who needs them, damn it. I already have more than I should."

"I am offering them to someone who needs them," Father Christmas replies.

When Lena opens her eyes, he's gone.

To bed, then. Lena does a thorough circuit of her apartment, checking to be sure the windows are all latched and the door is locked and no one is lurking in any closets or around any corners. In the morning she'll confirm with security that all was undisturbed in the night, that it was a bad dream, that her alcoholism has become so far advanced that she is now imagining mythical figures in technicolor and should probably see a doctor. Maybe also a therapist. Maybe a fucking priest.

Her last thought as she drifts off is that it's a nice idea that there might be a real Father Christmas out there somewhere, doing his best to to bring the Christmas Spirit to the multiverse all by himself. She wonders how many places he can really be at once. In the end, she supposes it doesn't matter; he was never real.

In the morning, she's woken by a loud crack. She's out of her bed, weapon in hand, in two seconds flat. There are the skills she learned from the Luthors, and then there are the skills that came with her precarious status as the last Luthor still living. Lena has only ever once wished she'd had a firearm, and it was the second worst day of her life; she'll be damned if she's caught unprepared again. She ventures into the living room quickly but quietly, listening, but there's nothing. Nothing but the sound of her own heartbeat and a rising feeling of foolishness that she should be so paranoid even after all these years. Probably a bird smacked into the window and in her hungover state - and it is becoming increasingly clear that Lena is _very_ hungover - she is reacting entirely out of proportion.

Except - no. There on the balcony is a figure lying on its back, dressed all in blue, shrouded by red cloth. Lena hovers in the doorway, her firearm raised, her heart uncertain. Paranoia says this stranger means her harm. Reason says he's somehow fallen, though from where exactly Lena can't imagine, and is likely badly injured.

She, Lena realizes, as the figure pulls herself to her feet. She is definitely a woman, and the most beautiful woman Lena has ever seen. She wears a blue tunic with a bold golden S emblazoned over the heart, and a red cloak around her shoulders out of which she shakes a significant quantity of dust.

She fixes Lena with an apologetic smile. "Sorry," she says. "We can pay for the damages. I'll be back, I swear, I just need to-"

And then to Lena's horror and amazement, in that order, the stranger leaps off the balcony only to come to an abrupt halt, hovering several hundred feet above the streets of National City. Lena wonders if perhaps she's still drunk, because it's the only explanation she can think of for the the appearance of a cloaked stranger who can inexplicably fly. There isn't time to give the matter much thought, because the stranger turns in a slow circle, her expression visibly troubled, and then alights - gently this time - on Lena's balcony and taps on the window. Looking back, Lena will never be quite sure why she let a stranger, especially such a strange stranger, into her home. But she does. She unlatches the door and steps aside as the young woman before her takes great care to knock the dust from her red boots and comes inside.

"I'm really sorry to impose on you like this," the stranger says, fixing Lena with eyes so deeply blue that for a moment Lena really does feel drunk, "But where exactly are we?"


	2. Chapter 2

"National City. National City. But not my National City. Do you know which Earth this is?"

Lena thinks about her Father Christmas hallucination. _An infinite number of worlds..._ She scoops up the bottle of whisky from the coffee table and stows it in the cabinet, her fingers trembling, hoping against all logic that her cloaked stranger hasn't seen it. Not that it matters. What should she care what a stranger thinks of her? What is it to anyone if she has a drink or a few drinks in the comfort of her own home? It's Christmas, for Christ's sake. No pun intended. Lena figures that anyone who can drink is doing plenty of that this time of year.

And yet something about the stranger in her living room prompts her to feel a quiet burning shame about the whole thing. She deposits her glass in the kitchen and calls out, "Would you like some coffee?" Mostly to avoid the question about which Earth they're standing on, which carries a lot of implications Lena is not prepared to sit with, but partly because this hangover isn't going to get any better on its own.

"Your Earth still has coffee? Gosh. Yes, please!"

Lena frowns, fingers busy with the machine. "What do you mean? You don't have coffee where you're from?"

"It died out almost a decade ago. Wow, I haven't smelled that since... wow. Thank you."

They stand together in the kitchen for some time smelling the coffee as it brews until abruptly the stranger wipes her hand on the front of her tunic and offers it to Lena.

"I'm sorry; I never introduced myself. I'm Supergirl."

The woman can fly, and _that's_ the superhero name she goes with? Well, to each their own, Lena supposes. She takes the offered hand and tries to push down the squirming feeling in her stomach at the warmth and strength of Supergirl's grip. It's the hangover. That's all. "Lena Luthor," Lena replies.

Supergirl goes very still. It's only for a second, but Lena has been reading the behavior of others for a long time; little is lost on her. "Luthor as in Lex Luthor?" Supergirl asks.

Maybe she really is from another Earth if she has to ask Lena such a question. After all, Lex's murder at the hands of Gotham City's vigilante prince is such a famous story, and Lena so famous by proxy, that no one has questioned her identity or her relationship to Lex for more than six years.

"Lex was my brother, yes," Lena replies. She pulls both of her mugs down from the cupboard and quietly thanks every star in the sky that the housekeeper was here yesterday, because otherwise she'd be serving coffee in a wine glass.

"Was?"

"He's dead," Lena says shortly. She flashes Supergirl a strained smile. "He was murdered trying to rescue me from a hostage situation; I'd rather not talk about it."

A long silence passes between them. The coffee machine declares with a last gurgle that it's finished its work, and Lena pours mostly to fill the quiet.

"I'm sorry," Supergirl says at last. "On my Earth, Lex is... not a good person. The Luthors and my family have a long history."

Lena smiles bitterly as she passes Supergirl a mug. "He wasn't a good person on my Earth either. But he was still my brother, you know? Cream and sugar?"

"Please," Kara says. She takes a sip of the coffee black and closes her eyes for a moment of indulgence.

"Unfortunately I can't tell you what Earth we're on, because on my Earth, the multiple worlds theory is still just a theory. Nobody here can fly, and certainly nobody here that I know of has ever passed into an alternate universe. So if there's a naming or number convention, I'm afraid I don't know it. But if you need help getting back-"

"As soon as possible," Supergirl interrupts with a curt nod. "Do you have The Flash?"

"I assume you're not talking about a smartphone camera feature," Lena says dryly. She motions towards the living room and they settle there, Lena on one end of the couch and Supergirl on the other. Supergirl keeps both hands wrapped around her coffee as though for warmth.

"I'm talking about the fastest man alive," Supergirl explains. "What about Star Laboratories?"

Lena shakes her head. "I've never heard of it, but if it's a small facility-"

"It isn't. You'd have heard of it. Shoot, Flash could have just run me back to my universe. What about the DEO? Or Batman?"

Lena flinches. "Batman is not the kind of person you go to for help."

Supergirl watches her thoughtfully for a long moment, and then looks down into her coffee. "He killed your brother," she says. It isn't a question. "There's no Superman on your Earth?"

"No," Lena says. The coffee has turned tasteless in her mouth. "We have no heroes here."

"So Bruce and Lex would have been natural enemies, then."

Lena says nothing. Bruce and Lex were, indeed, natural enemies, each trying to outdo the other in doing good until doing good became exercising control over their cities, their regions, and now in Bruce's case the nation. They say that power corrupts, and in her experience it has been true. The only thing that corrupts more absolutely is the absence of competition. She thinks of the firearm strapped to the underside of the coffee table and wonders for the thousandth time when she'll do or say or manufacture the wrong thing, and draw Bruce Wayne back into her life.

"LuthorCorp is the second most powerful company in the world," Lena comments. "If it's resources you need, I'm more than happy to connect you to them."

Supergirl raises her eyebrows. "Travel between universes can be expensive."

"It's Christmas. Every stranger is the son of God or something, isn't that right? What you do to the least of you? Not that you're the least of anything," Lena comments with a flush, "But it's in the spirit of the season so just... so just tell me what it is you need." She can practically hear Lilian making sarcastic comments from the grave. What is this bumbling performance? Since when does Lena care about 'the spirit of the season' anyway? It's this Goddamn hangover.

"We'll have to work quickly," Supergirl says, leaning forward.

"You have a fight to get back to?"

She smirks. "Hardly. Dreamer was about to finish it; I was just taking the hits as a distraction."

"I'm sorry, something _hit_ you and that's how you crossed universes?"

Kara shrugs. "He has a mean right hook. Anyway, but it's Christmas time and I know it's asking a lot but in the 'spirit of the season' I really would like to get home in time to be with my sister for the holiday. It's her first Christmas since her fiance passed away and I would just. I'd just like to be there with her."

Lena nods slowly. She knows something about first Christmases after a loss, after all. And there is something about the woman sitting across from her in a superhero costume sipping coffee for the first time in ten years and talking earnestly about getting punched into another dimension as if that were a totally normal thing to discuss on a Sunday morning, there is something about her that leaves Lena feeling as though there isn't a damn thing she wouldn't do for her.

"Okay," she says. "So how do we get you home?"

They're at LuthorCorp by late morning. Supergirl arguably shouldn't be seen walking around National City in her costume, and so she's changed her blue tunic for an oversized sleep sweater of Lena's, which has the effect of making her look less like a superhero and more like a young woman on the cutting edge of athleisure fashion. Lena tries not to think about how soft and welcoming Supergirl looks in that sweater, even as she fills out the shoulders in a way that Lena never could. She calls Jess while Supergirl is getting changed and tells her to call the engineers and see if anyone is available for a volunteer project. Strictly volunteer. It is, after all, the holidays; there will be a bonus provided, but Jess isn't to mention it over the phone in case anyone feels bribed. Four volunteers answer the call.

Among them is Cisco Ramon, who is waiting in the conference room when Lena and Supergirl arrive. He eyes Supergirl curiously as she sits down across from him and busies herself with Lena's computer, pulling up the schematics she sketched out from memory while Lena was in the shower. She shoots Cisco studious glances as she works, and Lena privately wonders whether they know one another in another world.

"I worked this out ages ago with my friend Barry," Supergirl explains. "A sort of 'just in case' measure. You don't want to get stranded in an alternate dimension if you can help it, right? So you need a design simple enough to be fabricated on short notice, and the principle of the thing is that it will get you back across the boundaries of space and time. Not sure which universe you'll land in, but ultimately you just need to get to an Earth already connected to the multiverse by more advanced technology and then a hopscotch across to Earth-72 and boom, it's as easy as that. If it's not an Earth connected to the multiverse, you just... try again."

Cisco gives the schematics, now projected on the wall, a cursory appraisal. "Just so we're clear," he says, "You're asking me to build an inter-dimensional trebuchet."

Supergirl bobs her head, her bottom lip between her teeth. "Yeah, yep, that's pretty much it."

"Just so we're clear," Cisco says again, "This will absolutely kill you. Long before you come close to crossing the boundaries of space and time." It's to Ciscos's credit that, despite having no explanation for the short-notice holiday project or the absurd schematics in front of him, he hasn't yet asked who Supergirl is, or why it is she might need to cross into an alternate dimension, or how she knows such a thing is even possible, or whether anyone has confirmed that the 'multiverse' as it were actually exists. That his primary concern is the survivability of the proposed contraption prompts Lena to ask Jess later what they actually hired him for and whether it might be time to consider a promotion.

Supergirl glances at Lena as she worries at her bottom lip, and then back at Cisco. "So it's a long story, but basically? I'll be fine. I was in a fight with a really big dude and he punched me so hard that I landed in your dimension but I really need to get home so that my sister isn't drinking alone on Christmas and that catapult is honestly my best plan. So can you do it?"

Cisco opens his month, closes it again, and frowns at the schematics. There is a tense moment while Lena waits for him to ask who Supergirl is or how she survived such a thing, but he never does. "Your universe sounds awesome," he comments. "Yeah, I can get you home. By Christmas?"

"Please," Lena says. "If you have the time."

"If I have the time? To build an inter-dimensional trebuchet? This is the best project I've ever been paid to attempt, I absolutely have the time. But hey, you did mention something about more advanced technology linking Earths to the multiverse...?"

Supergirl smiles. "Build me the catapult," she says, "And I'll write out everything I know for you. For LuthorCorp," she clarifies with a quick smile in Lena's direction. "As a thank you for getting me home."

Cisco grins. "Trebuchet," he corrects. "It's a deal. Give me two days and access to the mountain facility.'

"Granted," Lena replies.

"Two days," Supergirl says when Cisco has left the room. "Christmas Eve. I can't thank you enough, Lena, I-"

"It's nothing."

"It's not nothing." Supergirl reaches across the table to squeeze Lena's hand, and for a moment Lena stops breathing. She weaves her fingers through Supergirl's with a tight smile, ignoring the way her heartreate picks up, shoving down the warmth that flares up inside of her. Hangover. Just a hangover. This is going to pass. Supergirl is a pretty stranger whose real name Lena doesn't even know, and she's leaving in two days, and to catch feelings for her would be unwise at best. Already two days doesn't feel like enough time. Already she doesn't want Supergirl to go.

"You'll stay with me the device is ready," Lena says. Oh, she could book a room for Supergirl, she could hand her a company card and set her loose in the world, but that doesn't seem like the polite thing to do, and far be it from Lena to be a poor host. "And then we'll get you back to your sister."

"I'll need computer access so that I can copy down what I know about inter-dimensional travel. It's an incomplete picture, but it could move your Earth's progress forward by a few years."

"Maybe by a few decades," Lena comments. She tries not to let her mind linger on the fact that Supergirl hasn't pulled her hand away. "Until you fell out of the sky, nobody was even sure there were dimensions to which we might consider traveling."

Supergirl laughs. It's such a bright sound, so full of joy, and Lena thinks she would move heaven and earth just to hear it again, "I didn't fall out of the sky, really. I fell out of- I don't know. I got very lucky."

"Did you?"

"I did," Supergirl says with a flush. She squeezes Lena's fingers. "At least I think I did."

If Supergirl is going to survive for two days in Lena's National City without incident, there are things she's going to need. Maybe if Lena were a warmer, more hospitable person she would have spare things in her apartment in case of a guest, or maybe if Lena were more likely to have a suitor over for the night, or perhaps if she had been in National City for longer than a year, but none of those things are true, and so she is woefully underprepared. She has a spare towel and that's about the end of it.

So she arranges a trip downtown despite Supergirl's protestations so that they can pick up a few necessities and perhaps a few luxuries to make her more comfortable. Clean clothes, for example. Cozy pajamas. An appropriately festive hat, maybe.

"But I won't be able to take them with me back to my world," Supergirl says for the hundredth time. "You really don't need to spend any money on me; I'm fine."

Lena threads her arm through Supergirl's with a frown. "Last time I checked I had something in the neighborhood of sixty seven billion dollars to my name. I can afford to be a good host, and when you leave, I'll have the clothes cleaned and donated to someone who needs them. Fair?"

It's the right thing to say. It's the right thing to say every time Supergirl gets anxious and uncomfortable about Lena spending money on her until finally Supergirl's anxiety is reduced to a silent nibbling of the bottom lip to which Lena invariably responds by taking her arm or by resting a hand on the small of her back.

So it is that Supergirl steps out of the changing room at one of Lena's favorite stores having transformed at once from an athliesure influencer to something altogether more charming. She stands before Lena in a pair of tight chinos and a button down shirt with the sleeves rolled up and the top two buttons conspicuously undone, her hair pulled half back - Lena has no idea where she found a hair tie - and a shy smile playing over her lips.

"What do you think?" she asks.

It takes Lena three or four seconds to get actual words out of her mouth. She licks her lips and nods. "Good. Yes. Five stars."

They leave the store with clothes for today and for the next two days, all variations on the same theme, and Lena is beginning to wonder if her hangover is ever going to let up because every time she looks at Supergirl in those pants, and every time Supergirl flexes under that shirt, she feels a little drunk all over again. Supergirl has somehow managed to procure pajama pants of which Lena approves (flannel in a blue that matches Supergirl's eyes) and a pajama top of which she absolutely does not (a baseball tee in dinosaur print). They never do find an appropriately festive hat.

When the necessities are gathered, Lena tugs Supergirl down the street to Union Square with every intention of taking her for lunch at the top of one of the hotels. It doesn't even matter which hotel; she'll go for whichever has the decorations Supergirlseems to like best. After all, if there is one thing Lena is confident her version of National City gets right, it's the holiday decor.

But when Union Square comes into sight, Supergirl stops short with a gasp. For a moment Lena thinks something is wrong, and her hand moves to the firearm in her bag with a glance back for the bodyguard who has been following them at a reasonable distance all morning. But Supergirl doesn't move, and when a few long seconds have passed, Lena realizes at last that what has startled her is the outdoor skating rink that occupies most of the square during the holiday season.

"Is that... real ice?" Supergirl asks. "Like really real?"

Lena laughs. "It's real. Do you want to touch it?"

Supergirl looks as though she might die of excitement. She actually bounces on the balls of her feet with a grin so big and goofy that Lena is ready to buy her the whole damn skating rink. "Can we really? Can we skate on it? Ohhh I haven't been skating since... I don't know. It's been a long time."

"Of course we can skate."

Officially there are no more spots available until much later in the afternoon, but Lena isn't a Luthor for nothing, and so a bare fifteen minutes later she's sitting on a bench watching Supergirl tighten the laces on a pair of rental skates, fingers shaking with excitement. When she gets to her feet she wobbles precariously for a moment, and when she finds her balance she looks at Lena with such pride that Lena almost wobbles herself.

They step onto the ice, Lena first and then Supergirl who takes it one ginger step at a time and clings to the wall for the first several feet. Sure she can fly, and she can take a beating, and who knows what other secrets are hiding behind those eyes, but she's as awkward and shy on the ice as anyone the first time out and when she makes her first hesitant push away from the wall at last it's only to fall, laughing, into Lena's waiting arms. Lena holds her steady on the ice, slowly pulling them backwards around the rink.

"This is so much fun," Supergirl whispers, her lips a hairs breadth away from Lena's ear.

Lena shivers. "It is," she says.

"Oh, are you cold? We could- we don't have to stay-"

Lena pokes Supergirl hard in the ribs, earning an indignant squeak and a few inches of breathing room. "We can stay as long as you like," she says, "We can stay all day if you want."

They stay for an hour. It takes some time, but Supergirl manages a lap around the rink by herself, and then two, and then Lena is teaching her to skate backwards, and how to stop without running into anything or dropping to the ice, and how to do a spin without falling. Supergirl's eyes are bright and her smile brighter and she takes all of Lena's instruction with a breathless enthusiasm which is only adding to her charm by the minute.

And then abruptly Supergirl announces that she's hungry and they're stepping stiff legged back onto solid land and trading their skates for their shoes with plenty of wistful smiles and stolen glances between the two of them. Supergirl puts her arm around Lena as they leave - "I don't want you to be cold, that's all," - and Lena doesn't resist. They do a slow lap around Union Square looking up at all the lights, the wreathes, giant ribbons, and towering trees decorated from top to bottom.

Lena is just about to ask Supergirl what she thinks she might like for lunch when Supergirl tugs her to a stop and points up with a shy smile.

"Holly," Supergirl explains. "We have to kiss."

Lena's mouth is suddenly very dry. "You're thinking of mistletoe," she says.

"What? No. There's hardly any mistletoe around; if it were mistletoe you'd never get to kiss anyone."

"If it were holly you would be kissing everyone all the time," Lena counters.

"Do you not want to?"

"Kiss everyone all the time?"

"No, kiss me." Supergirl's bottom lip has found its way between her teeth again. "Did I read you wrong? I'm sorry, I-"

Lena feels the moment slipping from her, and in an instant she sees how it will all play out: Supergirl will pull away, and things will become awkward and formal, and they'll be strictly professional until such a time as Lena has to say goodbye to her forever and that will be it. That will be all of it. And Lena will never know... what exactly? But whatever it is, the thought of never knowing it fills her with an indescribable sadness, and so she acts.

Her intention is to give Supergirl a chaste kiss, closed mouth, quick but warm, enough to say _I'm interested but I don't know how interested yet_. That's the plan. But when her lips brush against Supergirl's, the plan flies abruptly out the window. Supergirl's mouth is soft and warm, and the second Lena is kissing her, Supergirl is pulling her close, one arm slipping around her waist, the other tangling in her hair, and Supergirl's hips are suddenly pressed up against her and oh God it's a lot. It's a lot even before Lena feels Supergirl's tongue flicker across her lip.

Lena's legs go weak as Supergirl licks into her mouth, but it doesn't matter, because the arm around her waist is holding her up and Lena feels as though she could and probably will melt right here under this sprig of holly, Supergirl kissing her with such singular care and attention that Lena is suddenly certain she's never been properly kissed before in her life. She feels fingers tighten in her hair and pull ever so gently, and the moan that comes out of her is almost embarrassing except that she can feel Supergirl smile into her mouth. Supergirl nips her lip and pulls away, eyes searching Lena's for something, something.

"Supergirl," Lena murmurs. She's still feeling weak at the knees, and grateful that Supergirl hasn't properly pulled away yet.

"Kara," Supergirl whispers. "It's Kara Danvers."

Lena feels a rush of warmth that she is absolutely sure has nothing to do with her hangover. "Kara," she repeats. "It's lovely to finally make your acquaintance."


	3. Chapter 3

**Notes for the Chapter:**

> This chapter is tbh about 50% smut. If that's not your jam, skip it. The last chapter should be up by New Years!

Lena decides to walk home after lunch even though it's almost two miles, even though it takes them nearly an hour, even though she's wearing heels that err heavily on the side of fashion over function, because Supergirl - Kara - shows absolutely no hesitation when it comes to sweeping Lena into her arms every time they pass under, or by, or even reasonably close to anything that resembles holly. She whispers "Ms. Luthor, may I have the honor of a kiss?" And Lena always says yes. Yes even though her knees grow weak every time. Yes even though she can feel something in her shifting from interest to attraction to genuine affection for a woman she has only just met. For Kara, it's always going to be yes.

And so she's almost disappointed when they make it through the lobby - and another deep, lingering kiss outside of the elevator, much to the doorman's obvious surprise - and back into Lena's apartment where there is no Christmas decoration of any kind, let alone holly. Not that Lena doesn't consider having some delivered. She sets Kara up at the breakfast bar with a laptop and a notepad and a cup of coffee, and Kara dutifully begins her work transcribing her knowledge about interdimensional travel while Lena settles in behind her own laptop and tries not to be too obviously distracted.

And whether she succeeds in hiding it from Kara or not, she is absolutely distracted. She's distracted when Kara reaches for her coffee without taking her eyes off of the screen, by the way her brow furrows when she tastes it, by the soft smile on her lips as she works. God, she is distracted by those lips, so soft and so pink and so recently pressed against Lena's that she can almost summon to her memory the taste of Kara's mouth. She's distracted by those long graceful fingers dancing across the keyboard, by the muscles clearly defined under Kara's button down. She's distracted by the wisp of hair that keeps falling into Kara's face as she leans in closer to reread something on the screen, and by the line of her throat which Lena suspects could inspire a generation of artists, sculptors and painters and poets alike.

She is, in a word, fucked.

Because Kara is going to leave this universe forever in two days time if Cisco Ramon has anything to say about it, and Lena will be left with all of this wanting and nothing to show for it but half a textbook on interdimensional travel.

"Is there a Lena Luthor in your world?" Lena asks.

Kara looks up from what she's doing with a frown. "Lex is an only child as far as anyone knows," she says. "So I don't think so."

"Is that common? For a person to exist on one Earth but not another?"

"Well not as common as you'd think," Kara replies. "The multiverse operates according to rules we don't understand. Infinite universes, right? But we haven't discovered one yet where, for example, Earth has been destroyed, and probability states we should have. And by and large, the same people seem to exist at a fundamental level, even if in different circumstances or under different names or born to different parents. Marvel's Law and all that; I spent a whole semester on it in University. But the basic principle of the idea is that we are constrained to a 'neighborhood' of universes most similar to our own. Of course there are recorded exceptions at the macro and micro level. For example, there is a known universe in which the dinosaurs never died out. And there are some cases where we are as sure as we can possibly be that a person exists on one Earth but not another, but it's exceptionally rare and extremely difficult to prove. It would be much more difficult to prove that Kara Danvers doesn't exist on your Earth than it would be to prove that she does."

"Does she?"

Kara doesn't quite meet Lena's eye when she answers. "Maybe," is all she says.

They work in silence after that, until Lena orders dinner and they settle together on the couch with more Chinese food than Lena ever knew two people could eat in one sitting. Lena lets Kara pull her close when the food is gone, lets her maneuver Lena between her legs so that she's resting against Kara's chest, nose against her collar bone, surrounded by her warmth. It crosses Lena's mind that she's never felt so safe in her life as she does just now.

"May I kiss you," Kara asks after a while.

Lena half laughs as she looks up. "Why do you always ask?"

"A true Prince Charming always confirms consent," Kara recites.

Lena should be wondering where such an obviously rote memorization has come from, but the phrase 'prince charming' has sent a jolt down her spine. Could it be that Kara's presence in this universe is the result of Lena's sarcastic wish to Father Christmas? Which of course would require her to acknowledge that Father Christmas is real, that he was here in her apartment, that Christmas miracles are in fact A Thing. Absurd. And yet, women who could fly were absurd 24hrs ago. The concept of the multiverse almost equally so. Well, if Kara truly is the answer to Lena's wish, then it's true what they say about being careful what you wish for, because to have such a wonderful being in her life for so short a time seems to Lena to be more cruel than never having her at all.

"Lena?" Kara asks, the concern as clear in her voice as the ring of a bell.

Lena shifts her weight and leans upwards to press a kiss to Kara's jaw, then to her neck, then to the throat Lena has been admiring all afternoon. Kara answers with a low hum that feels as though it travels straight though Lena's mouth to her hips in a line of burning arousal. Kara is dangerous and leaving and Lena should pull away. She doesn't resist when Kara tangles long fingers in her hair and pulls her up instead to capture her mouth in a kiss as deep and languorous as all those that have come before. The ease with which Kara moves her is a gentle reminder that Lena couldn't resist even if she wanted to, that she's powerless in these arms, and in that moment all the rational side of her that knows Kara would stop in an instant if Lena were to say the word falls silent.

Maybe Kara can feel Lena's unspoken surrender, because her attentions become more demanding. She licks boldly into Lena's mouth and tightens her fingers in Lena's hair, her other hand moving to cup Lena's ass and then squeeze so firmly that Lena is almost certain it will bruise and damn if she isn't somehow more aroused by the idea. She runs one hand flat over Kara's stomach, feels her muscles clench in answer under the taut fabric of her shirt, and moves to her collar to begin undoing the buttons one by one.

"Good girl," Kara whispers, hot and wet in Lena's ear, and Lena nearly falters on the buttons. Nearly. And then she's reaching under Kara to undo the clasp of her bra and sliding the bra and the shirt together over those firm shoulders, Kara's eyes burning into hers all the while, those hands holding her steady even as her own fingers tremble.

Kara slips her hand under the hem of Lena's blouse and then hesitates.

"May I?"

"You can do whatever you want to me," Lena answers. "I can't stop you." She lowers her head to trail kisses across Kara's collar bone, but Kara lifts her chin with her fingers to look her in the eye.

"I want your permission," Kara says.

The moment hovers between them. Lena sees it all play out for the second time: she can refuse Kara here and still put a professional distance between them, chalk the kissing up to politeness around a foreign holiday tradition (well... Kara will see through that but it's an excuse at least), and then they can fall into a stiff and formal relationship for the next 36hrs until Cisco figures out the trebuchet and Kara goes home to her own world. Or she can give in to the feelings of warmth and safety and want that Kara is coaxing from every inch of her, and fall maybe a little in love, and break her own heart when Cisco figures out the trebuchet and Kara goes home to her own world. She's fucked either way.

In the end the thing that makes the decision for her is the fear of not knowing. Not knowing what could have been. Not knowing how it could have felt. And so she nods and says to Kara, "You have it; you can take my shirt off." And when Kara's hands slide up her back, leaving Lena breathless and flushed under her touch, when she whispers into Lena's ear asking if she can remove her bra, Lena says yes.

She says yes to it all. She says yes when Kara suddenly reverses their positions and Lena finds herself underneath her, hands pinned above her head, and Kara murmurs, "Do you like this?" She says yes when Kara asks to touch her, undoes her pants without ever breaking eye contact and slips her hand inside to stroke Lena through her underpants until Lena is squirming with frustration.

She says yes a hundred thousand times when Kara finally moves her underpants to the side to stroke her fully, when she eases a finger into her and Lena feels desperate to be closer closer closer closer and so she keeps kissing Kara and pulling at her and whispering yes and yes and yes as Kara presses a second finger inside. She says yes when Kara picks up the pace, when she asks low and husky whether Lena is going to be a good girl for her, and then the orgasm is washing over her, and Lena thinks she's forgotten how to say anything at all.

Kara rearranges them again so that Lena is resting on her chest and they lay there for a while catching their breath. Lena runs her fingers lightly up and down Kara's side, feeling the muscles beneath her fingers and admiring how unbelievably soft Kara is for someone so solid and so strong. Then her fingers brush Kara's nipple, and Kara's hips jerk.

"Careful," Kara murmurs.

If Lena wanted to be careful, she wouldn't be half naked on the couch with a beautiful woman who is about to disappear from the universe forever. She thumbs over Kara's nipple and, finding the reaction she'd hoped for, replaces her fingers with her tongue until she's rewarded with an honest to God whine as Kara wriggles underneath her. She feels one of Kara's hands leave her waist to find purchase on the back of the couch as Lena's fingers fumble at the clasp of her belt.

"Is this okay?" Lena murmurs.

"Gosh," Kara breathes. "Yes. Please touch me. Just... go slowly."

Lena isn't sure she knows the meaning of the world 'slowly' just now but she does her best. Kara's pants are too tight to leave much in the way of maneuvering room, and so there is an awkward shuffle as Lena undoes the button to work them down over Kara's hips. She trails kisses over her abdomen as she works, here along her ribs, there under the curve of her breast, now just under her jaw where she seems to like it most.

And then at last her fingers find what they're seeking, and Kara jerks under her again with a gasp that turns into a low moan and threatens to undo Lena before she can finish her task. Lena finds her rhythm quickly, blindly because she can't bring herself to tear her eyes from Kara's face even as Kara tilts her head back and closes her eyes. Lena dedicates herself to memorizing every line of her, every angle, every freckle, every errant lock of hair. She wants to remember forever Kara biting her lower lip, fingers tearing into the back of the couch, muscles trembling, voice low and reverent when she whispers Lena's name. Lena wants to remember it all, right down to the moment Kara comes undone. When it's over, Kara pulls her up to settle against her chest again, wraps her arms around her and kisses the top of her head.

They fall asleep that way, tangled in one another on the couch, lights still on, Chinese leftovers still strewn across the coffee table. When she wakes just after dawn, Lena finds that Kara has pulled down the decorative throw from what's left of the couch. She's warm and safe, wrapped in Kara's arms, that steady heartbeat sounding in her ear, the rise and fall of every breath even and comforting in the early morning light. It all feels so incredibly normal. Lena figures she should feel uncomfortable. Uncomfortable about the mess, about having been intimate with someone she's only just met, about having slept half naked on the couch, about all of it. She should be so uncomfortable. She feels so at home.

The tears are a surprise. She reaches up a hand to wipe them from her cheek and finds that she can't stop them coming, and then Kara is awake and stroking patterns across Lena's bare back and whispering into her hair, "I know. I know."


	4. Chapter 4

December 23rd is a beautiful, glorious, perfect picture of hell.

They order breakfast in. Originally Kara expresses that she has some intention of cooking for Lena, but as she peruses the cupboards in the kitchen her incredulity grows until at last she exclaims, "Okay, you don't like to bake; I can understand not keeping flour in the house. But a frying pan? How do you eat without a frying pan?"

Lena holds up her cellphone. "I press the magic button and food arrives. No frying pan necessary."

Kara kisses her soundly, pries the phone from her grip, and announces that if they had more time they'd be spending the day on cooking lessons.

If they had more time. That's the bittersweet beauty of it. If they had more time, there is probably not a chance on any Earth they'd have fallen into such a close relationship so quickly. Certainly Lena wouldn't have allowed herself to get so close; it's the constant nagging urgency of _knowing_ Kara which drives her to permit such decidedly un-Luthor-like intimacy. And yet if they had more time, there is still so much more knowing to be done.

Lena watches Kara work after breakfast. Kara is the image of discipline and focus, her fingers flying over the keyboard, her expression closed, bottom lip tucked between her teeth more often than not. She has given up on holly as an excuse to steal kisses from Lena (she's given up on asking for them, for that matter) and instead takes every fresh cup of coffee Lena deposits at her elbow as her cue to pull Lena into her arms for a lingering kiss until, inevitably, she reminds Lena that she has a great deal of work and very little time with which to finish it. Lena is pretty sure she's never made so much coffee in her life. When Kara's cup is full, she alternates between trying to focus on her own work and coming up behind Kara to peer over her shoulder, arms wrapped around her waist, lips brushing against soft wisps of hair along her neck. Kara's quiet smile gives away her interest, but she refuses to be distracted.

Which is probably for the best, but that doesn't stop Lena from pouting about it. She has today. Today and maybe tomorrow. She wants ten years. Twenty years. A hundred years would not be enough. She wants to drag Kara away from the computer and into the city to talk for days and days. She wants to pull her into bed and keep her mouth too busy for words. She wants to travel with her across the boundaries of space and time, to see a thousand other worlds, to spend a thousand thousand nights safe in those arms.

They have lunch delivered, but they go out for dinner. It's Lena's idea. Even with the assistance of more than adequate quantities of coffee, Kara is becoming bleary eyed and irritable and Lena knows full well that forcing a person to continue uninterrupted work on a project in such a state tends to lead to poor results.

"You won't be here to correct any mistakes you might make," Lena points out. "And I think it's better to have incomplete information than inaccurate information."

Kara grumbles about it but she agrees.

The Lighthouse is an impossible restaurant to get into on short notice, but the head chef considers Lena to be personally responsible for the fact that his youngest boy survived his fight with leukemia, and so the impossible is handled in the space of a phone call. They make their way downtown in a LuthorCorp car, taking frequent detours to observe all the best Christmas displays in the city, and when they arrive, Kara scrambles out first so that she can open Lena's door for her - nevermind the fact that they have a driver to do that. Lena finds herself blushing, and she's almost angry about it because how dare Kara be so charming? But Lena can't muster more than an iota of anger for more than an instant.

They're seated under fairy lights beside a modest Christmas tree done up with burlap garlands and hand carved pine ornaments, positioned so as to experience both the oceanside view for which the restaurant is named and a clear line of sight to the open kitchen. Kara and Lena watch the chefs at work and sip wine and touch their knees together almost shyly under the table. Lena considers getting drunk - it would certainly take the edge off the bitter side of bittersweet - but in the end she decides that if this time is all she has with Kara, she wants to remember it. She'll remember it for the rest of her life, and never know whether to curse Father Christmas or bless him when she thinks of it.

Dinner is three courses and, after a quick consultation about allergies, completely out of Lena's hands. They pass the time laughing and sharing glances too full of meaning for two people who have only just met one another, swapping stories about one another's worlds and marveling over the the dishes brought to them by the chef. Lena is startled to discover that Kara's Earth has long since banned cattle ranching, and so the short ribs are a marvel to her. Kara is shocked to find out that Lena's Earth is still harvesting milk directly from live cows, a revelation which prompts Lena to ask a half dozen agricultural questions the answers to which leave her burning with curiosity about Kara's world and aching with the frustrating knowledge that she will never see it.

It isn't until dessert - caramel pear tart with creme fraiche and two perfectly pulled shots of espresso - that Kara finally brings up the elephant in the room.

"Do you believe in soul mates?" she asks.

Lena raises her eyebrows. "Little bit of a loaded question given the circumstances, don't you think?"

Kara laughs and turns away. "My friend Barry has been to... gosh, I don't know. Dozens of worlds. That's his job; he's made a career of mapping the multiverse. And he told me one night that in every world he visits, if there's a Barry Allen and an Iris West, they're in love. And I mean it hasn't always worked out, you know? Sometimes one of them is dead, or somebody is married to the wrong person, or life just gets in the way. Life has a way of doing that, I mean life can be a real jerk. But they're always in love."

Lena looks past Kara out the window to the long horizon line, sea meeting sky, shining faintly in the moonlight. "And in your world?"

Kara pushes a piece of pear across her plate with her fork. "In my world they're married. So." She looks up at Lena tentatively, not quite meeting her eyes. "Anyway, I was thinking maybe... maybe that's us. In love in every universe. Across universes."

Lena swallows the lump that has suddenly appeared in her throat. "I didn't know things had become so serious between us," she jokes.

Kara doesn't smile. "Yes you did."

Lena reaches for her hand and, after a long hesitation, Kara lets her take it. They sit there for a long moment not looking at one another, listening to the sounds of conversation all around, and the low twinkle of Christmas music overhead, and the hustle and bustle of the kitchen, and the waves crashing against the rocks outside.

"It's a pretty story," Lena admits.

Kara closes her eyes. "There's something I have to tell you."

The sounds of the restaurant are enough to offer a semblance of privacy and so, heart pounding in her ears, Lena nods. "I'm listening."

Eyes still closed, Kara continues. "I'm not from here. I mean not- I mean obviously you know that I'm not from your universe but even in my universe I'm not from here. I mean - shoot. I'm an alien, Lena."

Lena nods. This introduces maybe a hundred thousand questions to the equation, but Kara's posture says that she isn't quite finished speaking, so Lena bites them all back. "Okay, so that explains some of the flying and the super strength. Are aliens a common thing on your Earth?"

Kara chuckles and opens her eyes. "No. Well... No. Not unheard of but not common. Habitable planets are few and extremely far between; I know of only half a dozen still living, and only two with the means to travel from one to the next within a single lifespan. It's... space is punishingly large, you understand. Intersystem travel is more demanding than hopping from one universe to another; I'm afraid my Earth will be dead long before we've truly mastered it. But every so often we get a refugee, yes. We were even invaded by Daxam earlier this year. Turns out they'd rather have a dying planet than no planet at all. Not that I can blame them. It's a long story."

Lena rubs her thumb over the back of Kara's hand and Kara smiles at her weakly. "So you're from another planet, and Earth hasn't developed the technology to get you home?" Maybe this is is the answer. Maybe Kara will stay, and Lena can help her build a ship, and together they can find a way back, and-

"My planet died a long time ago," Kara whispers.

Oh.

"I'm sorry," Lena says.

Kara waves her away. "Two survivors. They sent my cousin Clark ahead in a pod, but he was killed on impact when he arrived on Earth. And me? I got caught in the phantom zone and didn't land for... gosh, for a long time. But then the Danvers family took me in, and I learned to love Earth for what it is. And I swore that I'd fight for it, that I'd never let what happened to Krypton happen again. Not that I'm doing a great job."

Lena squeezes her hand. "I'm sure you're doing everything you can."

"I'm not," Kara says, her voice hard. "But sometimes not all that is within your power is the right thing to do. Anyway. Off topic. What I'm trying to say is that I came to Earth because Krypton was destroyed. Now, in other universes Clark lands first and he becomes Superman. In a few universes we land at the same time, and in one case I land first. I've never heard of a universe where neither of us arrived at all, but I did a search of all the news sources on your planet and-"

"And no alien pods bearing children from a dead world, no. Not that we probably would have printed it in the news if it'd happened."

"There is no Kara Danvers on your Earth," Kara confirms, "I checked; I was thorough. And no Clark Kent either. But then I got to thinking that just because there's no Kara Danvers on your Earth doesn't mean she isn't in your universe. She's just... far away, on Krypton."

Krypton. "Your planet hasn't been destroyed in this universe?"

Kara shrugs. "I don't think so, no. But there's no way to be sure, really; it's too far away to see without a powerful telescope. You'd need a whole observatory and a clear night with no moon if you wanted half a chance at spotting Rao, and that still wouldn't tell you whether the planet lives. It's possible my planet was destroyed and I simply didn't make it. But what I'm saying, Lena, is that in your universe there's still a chance for us."

"I don't want another you," Lena says, suddenly sick to her stomach. Another Kara however many thousands upon thousands of lightyears away, lifetimes away, can never replace the flesh and blood woman sitting beside her.

"And I don't want another you," Kara replies gently, "But I want you to have a chance at happiness, and Lena... Barry grieves for the universes in which he and Iris are alone. I don't want that for you." To Lena's surprise Kara reaches into her shirt pocket for a usb drive which she slides across the table. "So I made you a map. It's a long journey-"

"An impossible journey-"

"But not impossible. You're a Luthor. And you have Cisco Ramon who... I mean I don't even know if you know what a gem you have with him. Cisco Ramon is one of the brightest minds on any world; if anyone can help you crack instersystem travel it's him."

"And what about you? Stay with me. Stay with me and crack it with us and when it's time-"

Kara shakes her head sadly. "I can't stay. My sister needs me. And too much time in the wrong universe you simply start to... fade away. It's a fascinating phenomenon, but I have too many promises to keep in my own universe to allow myself to become a ghost in yours."

So that's it then. Lena takes a deep breath, opens her mouth to speak, closes it again with tears in her eyes. Kara has to go home, and it doesn't matter what Lena says, and they'll be apart forever, and-

"Hey," Kara murmurs. She reaches up to brush a stray tear from Lena's cheek. "There's a chance. You and Cisco are going to build a ship. You're going to go out there into the stars, to Krypton, and you are going to see me again. And gosh, Lena, that other Kara? She'll know you when she sees you. I'd know you in any universe. Across universes. I knew you the moment I saw you."

Lena laughs despite the pain of it all, angrily wiping at her eyes with her free hand. If she's being honest, she knew Kara too. She may have sworn up and down that it was the hangover, but Goddamnit. She knew.

The call comes just before Lena's alarm goes off on the morning of Christmas Eve. Lena knows what it's about even before she answers it. She knows, and she considers hanging up before Cisco has a chance to speak, but in the end she can only put it off for so long and so she goes through the motions and tries not to hate Cisco for sounding so excited about the fact that he figures he's successfully created a contraption that will fling the one person Lena can really truly say she loves across the boundaries of space and time into a dimension from which Kara will probably never be able to find her way back.

"Our universes aren't linked," Kara explained on the way home from dinner. "With the right technology you can trace the path from one universe to another and in so doing sort of chart the course so that you can find your way back. My earring acts as an anchor to my home universe, but we don't have the technology here to create a second anchor or to chart the path back when I leave. Maybe one day..."

But Lena thinks they both know that 'maybe one day' means probably never. There are an infinite number of universes out there, and without a map, finding Lena's again would be like searching the sea for a bead of glass.

Cisco is saying something over the phone that Lena has only half heard. "Thank you," she says. "We'll be there in two hours."

Kara rolls over in bed, loops her arms around Lena's waist, and presses a kiss to her lower back. "I wish I could stay here with you forever," she whispers.

Lena takes a deep shuddering breath and says nothing.

They have breakfast in relative silence, and then a last cup of coffee for Kara, and a lingering kiss at the breakfast bar, and again at the door, and again when they get into the back of the car. Lena admires Kara in her Supergirl outfit one more time, that deep blue tunic, the S over her heart, the fairytale cloak. God. She wants to remember it all. She wants to remember all of Kara: every freckle, every breath, all the lines of her, the incredible gravity of her even when she is sitting still.

The mountain facility is alive with engineers when they arrive, but it feels empty to Lena but for the two of them walking hand in hand to the lot where Cisco has assembled the impossible in just under 48hrs. Kara hands off her work to him with a smile and a handshake. She admires his handiwork, checks over the numbers herself, talks shop with the engineers while Lena lingers in the background. It isn't that Lena doesn't understand the conversation or that she isn't interested, it's just that she can't bring herself to take her eyes off of Kara and she is afraid that if she opens her mouth to speak she will start to cry and she will never stop.

In the end the trebuchet meets Kara's specifications. Cisco leaves them in the observation room to do one last systems check. Kara sweeps Lena into her arms one last time and Lena digs her fingers into that cloak and refuses to let go.

"Don't leave me," she whispers.

Kara lets out a sob and pulls Lena impossibly closer, and it's Lena's turn to rub soothing patterns across her back, to murmur comforting things into Kara's ear even as Kara trembles against her and wets her hair with tears that won't stop coming.

At long last she pushes Lena away from her and, holding her at arms length, fixes her with a serious expression.

"You will go to Krypton," she says firmly. "You will find her. You aren't going to let this be goodbye forever, do you understand?"

"It won't be you," Lena chokes out.

Kara smiles sadly. "Don't watch," she says. "If you're watching, I don't know if I'll be able to go."

She's halfway out the door before Lena cries out, "Wait!"

"I love you," Kara says. She doesn't turn around.

"I love you too," Lena replies. "In any universe."

And then the door closes, and Kara is gone.

The ride back to the apartment is the easiest part. It is as though the Luther need to keep a straight face has turned the presence of the driver into a salve, or at least a numbing agent. She taps out an email to Jess regarding the bonus for the engineering team who built the trebuchet, and a promotion for Cisco effective immediately. A bonus for Jess too. And Merry Christmas. As soon as Lena sends the email she realizes she has no idea whether Christmas is a holiday Jess even celebrates.

It's all a thousand times more difficult when she steps through the front door of her apartment. Her quiet, empty, apartment. Closed on the breakfast bar is the laptop Kara has been using these past two days, and beside it is the mug from which she drank her coffee this morning. Lena stares at the scene for a long moment, imaging that she can almost see Kara slide into her stool, pop the laptop open, smile at Lena out of the corner of her eye, reach for the coffee... She can almost hear Kara let out a huff as she reads back over her work, can almost hear her voice...

But no. All Lena can see is a spare computer and a dirty dish. All she can hear is the wind.

She's crying before she realizes. She makes her way to the liquor cabinet with every intention of pouring herself a glass of whiskey, and when she gets there all she can think of is the embarrassment with which she hid that whiskey away when Kara first appeared on her balcony. Damn it. Damn it all to hell. She has the rest of the day to get through, and all of tomorrow, and all of the damn days after that, and all without Kara, forever.

She pours the whole bottle of whiskey down the drain. A shower, then. A long hot shower, and then she'll order lunch in - but not Chinese; Lena doesn't think she'll ever have another potsticker without thinking of Kara. She'll call Sam and Sam will tell her how stupid she is for getting hung up over some girl she met two days ago and how crazy it all sounds and what a ridiculous notion it is that somewhere out there in another arm of the galaxy there might be a young woman for whom Lena was made.

Ridiculous. Soulmates are such a ridiculous idea. And even if they weren't, one would think the universe would conspire to at least match people who live in the same solar system.

When Lena gets to the bedroom she freezes. The bed is unmade where she and Kara left it this morning, but Kara's clothes are folded neatly on top of the sheets: a pair of pants, three button down shirts, and the pajamas she never wore. Lena lifts yesterday's shirt from the stack and crushes it to her chest, presses her nose to the fabric for traces of Kara's smell.

Ridiculous. This is all ridiculous. It's ridiculous that any of it happened and it's ridiculous that Lena can't stop crying. At least, that's what she tells herself. She lifts the whole pile of clothes, intending to drop them in a bag and leave them by the door until someone can come and get them, but underneath is a usb drive.

And that's strange. Strange because the drive Kara gave her with that stupid, ridiculous, useless map is still sitting in Lena's pocket. Strange because the drive on which Kara backed up all of her knowledge about interdimensional travel is safely in Cisco's hands. This is something else.

Lena showers first, but she doesn't change into clean clothes; the thought of wearing something that Kara never touched feels unbearable and she hates herself for it. Still, it's easier to put the same damn shirt on than it is to wrestle down the panic and the grief that comes when she tries to pick a new one out of the closet.

She settles down at the breakfast bar with a mug of coffee - Kara's mug remains untouched where it stands - and pops the usb drive into the laptop. When she opens the screen, Kara's work on interdimensional travel is still open. _The principles that govern travel between universes are deceptively simple,_ Kara writes. Simple indeed. Her document is barely twenty pages long. So what was she working on that whole time?

The computer asks what Lena would like done with the usb, and so she commands it to show files. An untitled word document and nothing more. Lena opens it with a mouth full of anxiety.

 _Kryptonian: The Basics._ Forty seven pages. Lena sounds out the opening phrase slowly, painstakingly, one syllable at a time, feeling all the while as though Kara were hovering at her shoulder helping her to read the words.

_My name is Lena Luthor; I am an emissary from Earth. I am looking for Kara Zor El._

Lena thinks of Kara sitting at that laptop, tabbing open the interdimensional travel document as Lena leans in over her shoulder, reminding her with a sad smile that she has a great deal to do before she leaves. A great deal to do to be sure that when Lena figures out how to cross an impossible distance to a planet that may or may not even still exist, she will be able to tell someone what it is she's come all that way to find.

When the tears stop, Lena calls Jess. Nevermind that it's Christmas Eve. Nevermind that her voice is still thick from crying. Nevermind it all. Lena is a little surprised that Jess answers the phone.

"Miss Luthor?" She says.

"Jess. Can you find out for me who owns that observatory up in the mountains? You know the one I'm talking about?"

"Yes I do; it's owned by a private university. Did you want me to arrange a visit?"

Lena laughs in spite of herself. "I want you to arrange an acquisition. Buy the whole university if you have to; I don't care. There's someone out there I need to find."

"Something," Jess corrects.

"No," Lena replies with a smile. She runs her finger absently over the handle of Kara's mug. "Someone."

**Notes for the Chapter:**

> Maybe an epilogue to come? Thank you for reading! Find me on Tumblr at oreoambitions :)


	5. epilogue

Kara stands outside on the balcony, leaning out over the railing, her back to the party. For what it's worth, it's a beautiful night. For what it's worth, she's happy it only took two jumps to make it home to her own universe, that she's back among the family and friends who mean so much to her. And yet.

She can hear laughter drifting into the night from the apartment behind her, Winn's voice announcing that the second round of pizzas has just arrived, Alex groaning just before the jenga tower on the coffee table finally shudders and collapses with a resounding crash. Lights are on all across the city tonight - New Year's Eve is the last chance to spend the last of the year's power ration, after all - and it's gorgeous in its own way. Nothing like Lena's National City, of course, stretching from the dark quiet of the sea to the towering silence of the mountains, an ocean of twinkling lights and automobiles that feels like maybe it could go on forever.

Well, nothing goes forever. Kara's National City, with its dark streets and its subdued atmosphere, is proof enough of that. But maybe. Maybe with the knowledge that Kara left in the hands of Earth 73's Cisco Ramon, there is a chance Lena's Earth will figure things out before it gets this hard. And if not, well, there is a chance Lena will have a way out.

Kara looks to the stars with a longing that is at once painful and sweet. She knows, of course, that Lena isn't out there. Kara could, given an appropriate ship and adequate fuel, travel the universe from end to the other, and never would she find Earth 73 and its Lena Luthor. Still... It's only natural that when one thinks fondly of someone who is Not Here, they should look out into the great big Somewhere the stars have represented for however many billions of years. It's only human. Kara smiles in spite of herself.

She hears Barry disentangling himself from the group to make his way to the balcony, but she doesn't turn around. Let him come if he'd like. There isn't a person here who hasn't asked Kara what happened to her in the time she was away, not a single one, except for Barry. Barry, who watched her flash that bright smile and laugh off their questions and wave them away like it was nothing. Barry, who has been to so many worlds that the modern approach to charting the pathways between universes is referred to as the Allen Method. Barry, who never had to ask.

He comes up to the balcony railing next to her, rubs his hands together a little for warmth, steals a glance at her and then follows her gaze up to the stars. They stand there together in silence for some time, listening to the celebration, contemplating forever.

"So," Barry says.

"So," Kara replies.

"In my line of work you learn pretty quick not to make assumptions about things, but I'm going to go out on a limb here..."

Kara lets out a laugh so soft it's barely more than a puff of air. "We don't have to talk about it," she says.

"Well, the thing is, not talking about it won't make it not real. So."

And damn it Kara can't help the tears that spring to her eyes as he says it. She can't help the way her throat suddenly feels hot and thick, the way her fingers twist in the sleeves of her sweater as she looks away from the night sky. "I miss her," she whispers.

"So I was right; there is a her. Well, I thought it was going to be a him, but you know."

Kara laughs again, this time a little strangled. "Oh, so did I. But I looked at her and I just... And it never would have happened if I hadn't had this clock ticking in the back of my head. I have six days to get out of here or be trapped here forever and fade away into stardust, just a lost consciousness wandering a universe I can never really touch, but damn Barry. Once it started happening, I really did consider staying. I'm a terrible person."

Barry reaches out to rest a comforting hand on her forearm. "You're not a terrible person. She doesn't exist in our world?"

Kara shrugs helplessly. "I don't know. I haven't looked. I'm not ready yet, you know? There might be a version of her here, on this Earth. And if there is, she's... she's my Iris West, and I think I know that. I- Well, I do know that. But she's not the same person."

Barry nods. "Yeah, there's all that to consider. It's always a little strange encountering someone you love who is... someone else. But listen, if she's here-"

"And if she isn't?"

They don't say anything for a long time after that. Nia announces ten minutes until midnight, and the sorting out of champagne glasses for the big moment finally begins. Barry nudges Kara with his shoulder.

"You could go back, you know. Six days isn't much, but... Six days once a year is better than never."

The sob that wrenches its way out of Kara's throat is ugly and it hurts. She bows her head, her hands balled into fists. "I told her I couldn't," she whispers. "I said the earrings only anchored me to my own world, that I didn't have time to develop an anchor to hers."

"Okay, first of all that is a blatant lie, and if you really did hand everything you know about interdimensional travel to Earth 73's Cisco Ramon I give it maybe six months before she figures that out. If she shows up here to yell at you, I'm not going to back you up. But second of all... why? Was there another Kara on her Earth?"

Kara smiles at him sadly. "Not on her Earth, but I have reason to believe that her Krypton hasn't been destroyed. Kara Zor-El is waiting for her in the next arm of the galaxy. Barry, it would have been selfish of me not to lie. If I promised her I'd be there every year, every Christmas, she'd wait for me. She'd never go to the stars. And that's just not fair, because she can have me for six days a year, or she can have the Kara Zor-El of Earth 73 forever, and I just... I couldn't take that away from her."

Barry says nothing. There is nothing to say. He squeezes Kara's arm one more time, and they look up into the stars together, thinking about all the ways things could be different. Kara wonders if, in Lena's universe, Maggie is alive, if she's engaged to Alex, if they're happy. She wonders if Barry and Iris are married. She wonders if James and Lucy worked out after all.

"You know the hardest part about leaving Earth 73?" Kara muses.

"What's that?" Barry asks, his expression serious.

"They still have coffee."

Barry elbows her hard in the ribs with a grin. "Okay, I take it back, you are a terrible person but only because you didn't bring any back for the rest of us. Real coffee!"

They invite her inside for the countdown, and maybe she should go, but she waves them away. Alex gives her a long, lingering look, and she leaves the door open, but she lets Kara stay on the balcony. Kara listens to her friends chanting the countdown together in the living room. 3... 2... 1... silence.

The lights in the city blink off one by one, and Kara watches as candles flicker to life in the windows nearby. Slowly, softly, she hears voices rising up in the apartment behind her, in the building across the way, in the streets below.

_Should old acquaintance be forgot, and never brought to mind..._

Kara presses a kiss to the palm of her own hand and holds it up to the sky. Lena isn't out there, but maybe. Maybe she'll still feel this moment, the turning of the year, the acknowledgment of all they've left behind, the acknowledgment of all that is still to come, and all the love Kara wishes she could pour into her across the boundaries of space and time.

"I hope you find her," she whispers. "I hope you're happy."

It's three weeks before she musters the courage to take the next step.

In her defense, there is a lot to be done in those three weeks. A storm rips down the coast and Kara does what she can to help with the evacuation and the cleanup. She thinks of Lena's reassurance that she's sure Kara is doing all that she can, and she wonders for the thousandth time if she shouldn't just... seize control. Sometimes it's exhausting cleaning up after a humanity that refuses to look responsibility for its own demise in the eye.

For the thousandth time, she decides better of it.

When the storm has finally passed, when Kara has personally seen to the construction of new levees (again), when the fires in the North have been extinguished (again), and the low lying districts of Star City have been evacuated in anticipation of a record high sea surge (finally), Kara finds that she's running out of excuses. Either Lena Luthor is alive in her world or she isn't, and if she isn't, then what Barry said is true: not talking about it won't make it not real.

Kara lands on the roof of the DEO and takes the stairs two at a time to the command center. Barry is there, poring over a monitor with Alex, frowning about something on the screen. Winn is leaning back in his chair throwing a ball up and down mindlessly, his thoughts clearly far away. James passes through in the background with the announcement, "Something is on fire again; I will be right back."

Kara clears her throat.

"Winn," she says quietly.

Winn drops the ball on his face and scrambles to right himself. "Supergirl. Didn't see you there. What can I do for you?"

"I need you to find someone for me." She drops into the chair next to his. She's meant for this to be Not A Big Deal, but all activity in the command center has stopped to pay attention to her. Of course. Because all anyone has done since she got back from Earth 73 is worry and fret and ask if she's okay, and now, at last, she's showed up in the DEO to do something more than go through the motions.

"No problem," Winn says. He throws the database up on the big monitor so everyone can see. They're already listening; Kara lets it go. "Who am I looking for?"

"Lena Luthor."

Winn's fingers freeze over the keyboard. "Luthor like... Lex Luthor? The... evil guy who tried to kill you last week? And the week before that? And also lit that hospital on fire that one time? Oh, and-"

"Winn."

"Right. Sure. I can... just check to see if we overlooked a Luthor." He types the name in, and then looks back at Kara with an inquisitive frown. "I mean did he have a baby? Is this a grandparent? Estranged cousin?"

Barry meets Kara's eyes across the room, but his expression is impassive. "Just... do the damn search."

It takes a few minutes during which Kara feels her heartrate rising and her mouth going dry. Winn is thorough; he checks several databases, including a few to which Kara is pretty sure he shouldn't have access.

"Nope," Winn says with a shake of the head. "Definitely no one legally named Lena Luthor or using the alias Lena Luthor or any variation thereof, at least in any database I've ever heard of."

Barry straightens up. "Kara..." he starts.

Kara holds up a hand to silence him. She thinks of Lena, stretched out on the bed next to her, her nose pressed into Kara's shoulder, her fingers tracing soft patterns across Kara's stomach. She thinks of the small huff Lena makes right before she decides to tell Kara something that she thinks is Important. With a capital I. She thinks of that low voice and its whispered secret. _I'm not Lillian's daughter._

"Run a search for Lena Kieran. She may be the daughter of Helena Kieran."

Winn presses his lips together. "Okie doke. So is this more like a secret lover kind of situation? Are we looking for Lex's mistress, or- Oh, there she is."

Lena's face stares back at Kara from the screen. She's different, and yet... and yet the same. Those same knowing eyes. That same impudent stare. "Lex's sister," Kara explains. "His half sister. He doesn't know; we aren't going to tell him."

"Okay, well she looks pretty harmless," Winn says. He's scrolling through something on his own monitor. "I mean she works in a bookstore? Looks like she has a bachelor's in English Lit and a master's in History. She's got two overdue books at the Midvale library, but otherwise a squeaky clean record. Were you planning to take her in for questioning? Does she need protecting? What's the deal? Because I've got four teams on standby and if you want one, you'd better tell me before James gets back here with the 411 on..." Winn gestures vaguely. "Whatever he's dealing with."

Kara meets Barry's eyes again. He's watching her with a soft, knowing smile. Ever so slightly, he nods.

"I'll handle it myself," Kara says. She gets to her feet.

"Whoa, hold on. You aren't just gonna like... beat the crap out of this woman for being a Luthor, right?"

Kara laughs. "No," she says. "I think I'm going to marry her."

The flight to Midvale is short and uneventful. Kara lands outside the bookstore and then, suddenly self conscious, spends a moment outside straightening her cloak and brushing imagined lint off of her tunic. She's worried about first impressions. She's worried this Lena won't be the same. She pushes the door open. Maybe she won't even be here today, and-

"Can I help you?"

God, that voice. Kara stops dead in her tracks.

The woman comes around the corner slowly, distractedly. "If you're here about that order from- oh! Supergirl!"

They stare at one another in the half light of the bookstore. Those eyes. Those hands. That incredulous expression. The hardest part of all of this is going to be pretending that she doesn't know Lena already. Well, and why pretend? The world is a strange place. It's a new year. Time is always shorter than one imagines.

"Hi," Kara breathes. "This is going to sound ridiculous but uhm." She hesitates.

Lena deposits the stack of books she's holding onto a nearby stool and crosses her arms. "I'm listening," she says. Her eyes are still a little wide, but it's to her credit that she doesn't seem otherwise flustered by the fact that the head of Earth's superhero team is standing in her place of employment.

"Well... Gosh, this is awkward. I'm just going to say this, so... You know, if it seems weird..."

"The only thing that seems weird is that you won't just spit it out."

Ah, yes. And that's the Lena Luthor Kara knows and loves. She breaks into an easy smile. "Well so I actually met you - another you - in another universe and I... and she... Listen, you don't know me but I sort of know you - a version of you - and I-"

"Supergirl."

"Would you uhm. Hold on." Kara is gone for what will seem to Lena to be only a second, but which feels to her like an excruciatingly awkward length of time. When she returns, the breeze ruffling the covers of the books nearby and dislodging a stack of flyers from the counter, she holds out a fistful of fresh picked flowers. Okay, some of them are technically weeds, but they're still pretty and it's the thought that counts.

"I was just wondering if I could take you to dinner. Like. In a date way. In a- Gosh-"

Lena laughs. She takes the flowers from Kara's hand, a curious expression on her face. "Are you this awkward with all the ladies?"

Kara rubs the back of her head. "No?"

"I get off at 5," Lena says. "But I'm taking you to dinner, not the other way around; I don't know how many times you've saved the world but I'm sure I'm indirectly in your debt at least a dozen times over. The least I can do is buy a pretty girl a bite to eat."

Kara flushes at the words 'pretty girl' and opens her mouth to object.

Lena isn't finished talking. "You'll probably want to wear something a little less conspicuous though. We don't get a lot of superheroes in Midvale, so unless you'd like everyone from here to the diner to ask you for an autograph I'd consider a pair of jeans."

Kara can do jeans. Jeans and a nice buttondown, maybe. She's willing to bet this Lena will appreciate that look as much as the Lena of earth 73 does.

"Okay," she breathes. "5 o'clock. Dinner. I'll be there. Here. I'll be here at 5."

"Don't be late," Lena replies. She has already turned away to deposit the flowers into a mason jar full of water which Kara is pretty sure Lena was using as a drinking glass. Still, there's that soft smile, the stolen glance at Kara before Kara walks away, and the whispered "God she's even more gorgeous in real life" that makes Kara flush again as the door swings shut behind her.

It's not a guarantee, of course, that things are going to work out. Life could always get in the way. Life has a way of doing that, after all. Still...

Kara turns back to catch one last glimpse of Lena through the front window of the bookstore.

There's a chance.

**Notes for the Chapter:**

> Y'ALL. Thank you SO much for the kudos and all the amazing comments! Wow! I had a lot of fun with this story, and I'm glad you enjoyed it!
> 
> I swore up and down that I was going to be done after chapter 4, and then I said I would be done after the epilogue, but now... Well, how would we feel about a sequel in which Lena travels to Krypton hoping to find both the love of her life and help for a world increasingly terrorized by Batman? What if Kara is the lightsaber wielding captain of a starship, desperate for an edge in an increasingly desperate war against Daxam?? What if there's ONLY ONE BED??? Anyway.
> 
> Watch this space or follow me on Tumblr (oreoambitions) for updates :)


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